Google, Marriott, UPS Pick Sides in 2012 Election

"Unless a company has adopted voluntary disclosure and the company adheres to its disclosure agreement, you do have a real problem with many companies keeping their political spending secret," said Freed, whose group is supporting roughly half of the shareholder proposals.

Shareholder activist groups such as the Center for Political Accountability argue that disclosing political contributions will encourage companies to fully investigate a politician or activist group before donating, thus avoiding public relations headaches that stem from being tied to unpopular politicians or political decisions.

"Our goal is try to get corporations to take a look at their values and when they are making political contributions they are making them in line with their values," said Julie Goodridge, the CEO of NorthStar Asset Management, Inc. in Boston, which is petitioning eight companies to put all prospective political contributions up for shareholder votes.

Target, the posterchild of political contributions that have backfired, was boycotted by gay rights supporters in 2010 after it donated $150,000 to MN Forward, a political group that then ran ads supporting Minnesota's GOP gubernatorial candidate Tom Emmer, who did not support gay marriage.

"Here is a company who goes out of its way to be supportive of the gay and lesbian community, yet it's making a big fat contribution to an organization that wants to tear that community apart," said Goodridge.

Following the Target backlash, Goodridge said NorthStar decided to investigate other companies in their portfolio that were "boycottable" because of potentially unpopular political donations.

But Bradley Smith, a former chairman of the Federal Election Commission, said the recent push for more transparency has less to do with protecting shareholders and more to do with pushing a liberal-leaning political agenda.

"People who really want to silence corporations have decided this is an effective way to silence their political opponents," Smith said. "The goal is to shut down corporate speech in America."

Smith said the recent concern over corporate disclosures of political donations, which was amplified by the Citizens United Supreme Court ruling in 2010, is "much ado about nothing in true substance."

"You can't make charitable contributions these days without offending a shareholder," Smith said, also pointing out that the percentage of its profits that most companies give to politicians is "so small for any given shareholder it's just never something that's been worried about."